This invention relates generally to shaped laminates and, more particularly, to a mold apparatus and method for molding clad products or partially clad products, which includes means to perform perimeter edge folding and perimeter trimming of a cladding layer in a single operation.
Current vehicle inner door panels comprise laminates of various types. In some inner door panels, a structural backing material is covered by an embossed covering, which is often vinyl. These panels are formed by bonding the covering to the backing in a mold which embosses the covering. Sometimes a filler material, such as cellulose or a foam sheet, is bonded between the backing and covering. After bonding, the periphery of these panels must be trimmed before vehicle installation. In the past, this trimming has been usually accomplished in a separate trim fixture.
The industry has developed a mold apparatus wherein the laminate is formed in a mold that also includes external trimming knives that provide a finished panel ready for vehicle installation. Such apparatus is shown in U.S. Pat. No. 4,692,108 to Cesano. All of the materials used in forming the Cesano type of laminated panel are preformed.
Another type of inner door panel in use is a laminate comprising a structural substrate of reinforced foam covered by a vinyl covering. This type of laminate is formed by placing the vinyl and reinforcing material in a mold and thereafter injecting foamable materials, which expand, set up and cure in the mold. After curing, this unfinished laminate requires further processing before it is ready for vehicle installation. It is removed from the mold and transferred to a trim fixture, where it is finally trimmed by accurately cutting the periphery with a water jet or the like.
Some problems attend this post-formation trimming operation. For example, the unfinished panel must be accurately positioned in the fixture. If it is not, the final panel will be out of dimension and unusable. Such a panel must be scrapped. Also, this post-formation trimming operation requires additional handling, equipment and labor.
It would be desirable to provide apparatus for forming a laminated panel which produces a finished panel needing no further processing.
It would be further desirable to provide a mold for forming a laminated panel comprising a structural foam backing having a decorative covering material that is ready for installation upon removal from the mold.
U.S. Pat. Nos. 4,243,456 (Cesano) and 4,328,067 (Cesano) disclose a laminating method and apparatus for making shaped laminates such as inner door panels for automobiles produced from a thermoplastic substrate and a flexible sheet material. A one-stroke operation molds, laminates, and cuts. The laminated products have protruding free edge portions so that cut edge portions can be subsequently covered with the protruding free edge portions. The apparatus and method do not provide for folding over of the laminate.
U.S. Pat. No. 4,327,049 (Miller) discloses a method of forming automotive headliners from a flat strip having laminated layers of resilient, cellular foamed plastic and a finish textile material. The strip is cut to form a flat blank which is heated to a temperature at which the foamed plastic loses its resilience. In its heated state, the blank is compressively formed and simultaneously trimmed in a mold to the desired size and contour. The cells adjacent the marginal edge of the blank are reduced in size to reduce the wall thickness of the blank. No edge folding takes place. Here, there is preferably a backing of a cellular thermoplastic material such as foamed polystyrene, an intermediate layer of a cellular, foamed thermoplastic such as polyurethane, and a finish layer formed of a thin textile material such as nylon.
U.S. Pat. No. 4,446,088 (Daines) discloses a method and mold for making an improved egg carton wherein an inwardly offset surface of the cover of the carton is cut in a plane transverse to the top of the cover. This disclosure is not directed to laminates, nor does it include a folding step.
U.S. Pat. No. 4,456,443 (Rabotski) discloses a steam chest molding process in general, wherein articles such as foamed boards or sheets are molded from expanded foam material, such as polystyrene. A cavity is filled with beads of partially expanded polystyrene and steam is used to completely expand the beads. The foam is then cooled with water.
U.S. Pat. No. 4,692,108 (Cesano) discloses a mold for the covering and trimming of products of plastics material, particularly for panels for the inside upholstery of motor vehicles. The covering material may be formed of plastic sheets, e.g., PVC, textile cloths, or fabrics. This covering material is heat secured to a sheet of any substantially rigid and heat formable (i.e. thermoplastic) material, e.g., polyolefins, and the like. Trimming knives are arranged in the female element of the mold, around the male element. The trimming knives are slidably guided transverse to the male element of the mold and are carried by slides either horizontally or at an angle of 0 to 15 degrees to the horizontal. The trimming knives first penetrate the plastic sheet and then cut both the covering material and the plastic sheet which simultaneously trims the edges of the plastic sheet and folds the covering material over so as to cover the edges of the plastic sheet.
U.S. Pat. No. 5,352,397 (Hara et al.) discloses a process for producing multilayer molded articles including folding of skin material over a back of a resin material. The skin material is supplied between a pair of molds and thermoplastic resin melt is supplied to form a multilayer molded article. At least one ejector is provided to fold an edge of the skin material toward the center of the mold over the back of the resin body. The skin material may be fabric, nets of fibers or resins, paper, metal foil or sheets, or a film of thermoplastic resin or elastomer or rubber. The thermoplastic resin melt may be expandable or nonexpandable resins such as thermoplastic resins (e.g., polypropylene, polyethylene, polystyrene, and the like). Numerous expansion members such as air cylinders or hydraulic cylinders are used both in the mold-closing direction and perpendicular to the mold-closing direction to effect the folding and trimming operations. Here, it would be desirable for folding and trimming to occur in substantially fewer steps.
U.S. Pat. No. 5,462,421 (Stein) discloses a method and mold for forming and trimming a shaped vehicle inner door panel. The panel includes a vinyl cover layer and a structural foam backing layer. Upper and lower mold members have peripheral seals which define a mold cavity when the mold is closed. A plurality of moveable trim blades are carried by the lower mold member adjacent the seal. The trim blades move between retracted, intermediate and extended positions. Hydraulic rams open and close the mold and move the trim blades. A cladding layer of vinyl and substrate are placed across the lower mold member and the mold is closed to seal the substrate and cladding layer about their periphery. As the mold closes, abutment surfaces on both mold members advance the trim blades to an intermediate position to pinch the cladding layer against the substrate inwardly of the peripheral seals. A two-part polyurethane liquid foam system is injected into the cavity. The liquid permeates the substrate and sets up within the area delimited by the trim blades. When the foam sets up, the trim blades are hydraulically extended to sever the substrate and cover layer and trim the door panel to its finished shape as the foam fully cures. The mold members are opened, the blades are spring retracted, and the finished door panel is removed.
U.S. Pat. No. 5,582,789 (Stein et al.) discloses a vehicle door panel manufacturing method that includes a first membrane with a foam backing, an apertured second membrane spread adjacent the foam backing of the first membrane, and a moldable rigid polymeric material providing a backing for the second membrane and supporting the membrane.
U.S. Pat. No. 5,718,791 (Spengler) discloses a method of laminating a trim panel and folding a cover sheet edge around the panel rim. A carrier frame holds the cover sheet material. A lower mold receives the substrate, while an upper mold laminates the cover sheet to the substrate. Edge-folding tools are laterally moveable and arranged around the perimeter of the upper mold. Here, the substrate is at least partially pre-formed and pre-molded.
U.S. Pat. No. 5,746,870 (Tomioka et al.) discloses a device for simultaneously carrying out vacuum forming, wrapping and trimming of a skin sheet about a base material in one molding stage.
The prior art also includes the in-mold edge folding and trimming of panels formed by structural reinforced injection molding (SRIM) using two-part polyurethane with encapsulated fiberglass mat construction and cladding laminates. The SRIM process requires a mold design specific to processing liquid materials which must include a liquid-tight seal around the full perimeter of the tool and necessarily precludes the ability to process materials in vertical platen molding machines. This requirement would also preclude the use of separate cutting surfaces in the male tool as the liquid will flash into gaps as small as 0.001xe2x80x3 creating severe tool maintenance problems.
Other processes exist today which feature the clad insert molded trim panels. None, however, is so complete after the molding step with partial cladding, edge folding, and trimming having taken place. Edge folding and trimming, for example, can not be accomplished in the molding operation of low-pressure injection molding or compression molding and must be done as a post mold operation. Partially clad products cannot be manufactured using the SRIM polyurethane process without extensive taping or masking of skin to keep the low viscosity liquid components from migrating to the visible side of the trim panel. Also, the male half of a SRIM mold must be liquid tight to keep polyurethane foam from building up in these areas. This process characteristic precludes the use of separate materials which can be used as cutting surfaces to extend blade life and obtain sharper cuts. In the SRIM process the foam build-up at the material interfaces is severe and requires extreme maintenance measures. In addition, the SRIM process requires a liquid tight seal around the entire perimeter of the trim panel. This is achieved by using the cladding layer which must cover the total area of the cavity with adequate runouts to seal against. This liquid tight requirement also precludes the possibility of running the mold in a vertical position as is the case with steam chest processing.
All references cited herein are incorporated herein by reference in their entireties.
Specifically, the present invention relates to a steam chest molding process using, for example, a foamable material such as a solid, pre-expanded polyolefin bead, e.g., expanded polypropylene (EPP) or expanded polyethylene (EPE), which is conveyed into a mold cavity behind a laminating material, i.e., a cladding layer. The present invention encompasses the need to perform many functions of laminated trim panel production in an initial molding step to eliminate as many post molding operations as possible. The elimination of these post-molding operations along with the labor and materials required to perform them is viewed as a significant advantage over current state of the art EPP and EPE molding capability. Among the tool functions featured in the molding process to which this invention will pertain are the ability to mold partially clad products, the ability to perform perimeter edge folding, and the ability to perform perimeter trimming of cladding layer. Molding, including folding and trimming of the cladding layer is accomplished without the need for post mold secondary operations. These improvements are associated with a number of process specific variables in the molding process. Among these are the ability to use vertical platens in the molding machines, the use of a shear edge shut-off in the molds to accommodate crush filling (a process by which the mold is partially closed, filled with expanded foamable material, and closed), thereby partially crushing the foamable materials, and the fact that the molding material is molded in the solid state as opposed to the liquid state typical of most other molding processes associated with the manufacture of the parts of the type described herein.
The present invention includes a mold apparatus and method for forming a shaped laminate in one step where the laminate includes a cladding layer and a foam backing layer. The apparatus includes a male mold half matable to a female mold half that define a mold cavity. An inlet is mounted on the mold apparatus for introducing foamable materials, such as solid, partially expanded resin, into the mold cavity. Edge folding members, carried by one of the mold halves, movable from a retracted position to an extended position, fold the cladding layer over at least part of the edge of the foam backing layer. Trim blades are located adjacent to the edge folding members movable from a retracted position adjacent the cavity to an extended position engaging the other mold half to sever the cladding layer to define the finished shape of the laminate. At least one driver, such as a mechanical, pneumatic, or hydraulic actuator, for opening and closing the mold halves and for moving the edge folding members from the retracted position to the extended position is provided.
Each of the trim blades may be movably mounted on one of the edge folding members. Each of the edge folding members is preferably inwardly movable by an edge folding member actuator. The edge folding member actuators may be hydraulically, or pneumatically operated or by a camming action of a camming surface on heel blocks located on one of the mold halves against a camming surface on corresponding edge folding members on the other mold half. Folding of the cladding layer over the foam backing layer thereby occurs. A biasing means, such as springs, may be associated with each edge folding member to return it to a retracted position upon mold opening after completion of the molding process. Preferably, each edge folding member is slidably mounted on one of the mold halves, such that closing of the mold halves with respect to one another causes the camming surfaces on the heel blocks and the camming surfaces on the edge folding members to engage to move the edge folding members upon mold closure. The heel blocks are preferably located on the male mold half whereby movement of the male mold half into the female mold half causes the camming action to move the edgefold slide inwardly to fold the cladding layer over the foam backing layer.
The foamable materials may be solid, partially expanded resin and may preferably be pre-expanded polypropylene beads or pre-expanded polystyrene beads. The mold apparatus preferably is adapted to perform a steam-chest molding process. The cladding layer is a preferably a layer of a textile, a thermoplastic polyolefin sheet, or a polyvinylchloride sheet. The cladding layer may have a backing material of, for example, crosslinked polypropylene, thermoplastic polyolefin, or polypropylene bonded to it prior to being molded in the mold apparatus. The cladding layer may be a bilaminate, a trilaminate, or other multilayer laminate. The male mold half and the female mold half may be oriented with their openings preferably in a vertical plane, but may be oriented on a horizontal or other plane. A crush fill process may be used with the present invention.
Preferably, the drivers includes a hydraulic cylinder for opening and closing the mold halves and hydraulic cylinders for moving the trim blades. Optionally, adjacent trim blades overlap one another and are adapted to be sequenced to trim adjacent edges of the cladding layers in alternating movements to allow overlapping of the trim blades at the male mold cutting surface thereby facilitating a complete separation of excess cladding layer.
The molding apparatus may receive a cladding layer that fully covers or partially covers a surface of the foam backing layer.
The molding apparatus may include compression pins and cores, carried by the male mold half, moveable by a compression pin actuator in the direction of die draw to a position adjacent the female mold half, to compress the cladding layer onto the female mold half. The cladding layer is thereby sealed against the female mold to prevent the foamable materials from migrating under the cladding. The compression pin actuator may be mechanical, pneumatic, or hydraulic. The molding apparatus may include an air compressor to compress the foamable materials during the introduction of the foamable materials into the mold cavity.
A method for forming the shaped laminate in a single step is also provided using the above apparatus. The edge folding members and the trim blades are moved to retracted positions using a driver. The cladding layer is loaded onto surfaces of the edge folding members adjacent the female mold half. The female mold is then closed with respect to the male mold half, using a driver, to form the mold cavity. The mold cavity is filled, through the inlet, with the foamable materials. Preferably, the steam chest process is used to fuse the foamable materials. Each edge fold slide is actuated, using a driver, to the extended position to fold the cladding layer over at least part of the edge of the foam backing layer. Each of the trim blades is actuated to the extended position engaging the other mold half to sever the cladding layer to define the finished shape of the laminate, and then actuated back to the retracted position. The female mold half is then opened with respect to the male mold half to withdraw the finished shaped laminate.
Optionally, the mold halves may be partially closed, the mold cavity is filled, and then the mold halves are fully closed the molds to further crush and densify the foamable material aiding to fuse and homogeneous fill the mold cavity.
Optionally, a sequentially moving adjacent trim blades may be included. Here, the trim blades overlap one another to trim adjacent edges of the cladding layers in alternating movements. This allows overlapping of the trim blades thereby facilitating a complete separation of excess cladding layer may also be included.
The method may include compressing the cladding layer onto the female mold using the compression pins to seal the cladding layer against the female mold to prevent the foamable materials from migrating under the cladding.
The method may include the step of filling the mold cavity with prepressurized foamable materials, i.e. beads having an increased internal air pressure.
Finally, the method may include the step of providing an air compressor and the step of compressing the foamable materials with the air compressor as part of the step of filling the mold cavity with the foamable materials such that the foamable materials are pre-compressed in the mold cavity.